Suplemento de 1,25 dihidroxicolecalciferol e redução de cálcio e fósforo disponível para frangos de corte

Abstract

The objective of this study was to evaluate the effects of 1.25 dihydroxycholecalciferol supplement and reduced calcium and available phosphorus for broilers. Two field experiments (males and females) were conducted, and 612 birds per sex were used in each experiment, totaling 1224 birds. It was used a randomized block design with six treatments: 0.0, 1.0, 2.0, 3.0, 4.0 and 5.0 μg of active vitamin D3/kg diet, with six replicates of 17 birds each. Diets were formulated by following the recommendations of the Brazilian tables of nutritional requirements of non-ruminant animals, except for calcium and available phosphorus (20% reduction) for stages 8 to 21, 22 to 35 and 36 to 42 days of age. At 21, 35 and 42 days of age, the birds were weighed to evaluate the performance (weight gain, feed intake and feed conversion). At 21 and 35 days of age, one bird of each experimental unit was slaughtered to remove the bones and to measure bone variables. Chemical and organic composition and breaking resistance force of tibiotarsus were evaluated. Bone percentage of collagenous protein (CP) and non-collagenous protein (NCP) and bone percentage of minerals (calcium, phosphorus, sodium, potassium and magnesium) were evaluated. At 42 days of age, four birds/replicate were taken and slaughtered for measurement of carcass dressing and noble cuts yield. The obtained data were submitted to analysis of variance in a randomized block design considering the level of 5% probability by the F test. Inclusion of active vitamin D3 influenced (p <0.05) weight gain and feed conversion at the levels of 1.0 and 2.0 μg/ kg of active vitamin D3 for broilers. Feed intake was not significantly different for the studied levels. For female broilers, there was no significant difference in weight gain (p>0.05), but feed intake decreased linearly as level of active vitamin D3 increased in the diet whereas feed conversion decreased by increasing the level of the vitamin. It is recommended supplement supply of up to 5.0 μg/kg for female broilers and from 1.0 to 2.0 μg/kg of active vitamin D3 in diets for broilers at 8 to 42 days of age. Carcass dressing and noble cuts yields of broilers (males and females) at 42 days were not affected by the treatments, neither were performance and breaking resistance force of chickens from 1 to 35 days of age. It is recommended 2.47 μg /kg of active vitamin D3/kg in the diet inasmuch as it provided a better CP deposition and less amount of NCP, indicating better bone quality.